>>7Anything messing with the brain is out the window for security reasons.
We have hardware attacks on CPUs right now.
Imagine hardware attacks on chips inside your brain, or even better wifi enabled brain-implant VR that kills you if you load a specially crafted webpage into your VR device - that contains no conventional malicious code but fries your brain because some RowSpectreMeltdown vulnerability allows it to alter memory/registers/etc by performing lots of brute force computations.
And i guarantee it will be WiFi enabled, since the other alternative is to plug your brain cable into a wall outlet.